lets get one thing straight: I love everything about the Dawn of War universe.
It is not going to kill WoW.
If anything will draw people away from WoW, it will probably be Diablo 3. I base this on what I have heard from most of my gaming friends and/or other WoW players that I know.
I personally am very excited for Diablo 3, mostly because any form of "scheduled gaming" is something I refuse to participate in. I want a game that I can play when I want, and *only* when I want.
By "scheduled gaming" I mean in-game events which are "optional" but end up becoming mandatory if you want to progress your character (getting loot, gaining achievements, progression through a dungeon, whatever)
As far as this Dawn of War MMO, I will indeed check it out. Truthfully, though, all I care about is Diablo 3.